Methods have been developed for preparation of uniformly-sized dispersed colloidal metal and metal-oxide nanoparticles via high-temperature thermolysis of organometallic species in non-polar, organic solvents. The particles are coordinated with organic ligands, and thus are within nanoparticle-containing complexes. The organic ligands may form a shield around the individual nanoparticles to prevent agglomeration of the nanoparticles with one another.
Uniformly-sized dispersed nanoparticles are particularly well-suited for many applications. Among the applications are utilization in semiconductor devices, and/or utilization as abrasive material for semiconductor device fabrication. For instance, nanoparticles may be utilized as charge-trapping centers of flash memory devices, and/or may be incorporated into slurries utilized for chemical-mechanical polishing (CMP) of surfaces during semiconductor device fabrication.
The nanoparticles are better suited for many applications if the nanoparticles are dispersed in water rather than being dispersed in organic liquid. For instance, water may be more compatible for utilization in semiconductor processing than organic liquids. Accordingly, it is desired to transfer the nanoparticles from organic liquid to water prior to utilization of the nanoparticles in some applications. Problems may occur during such transfer if the nanoparticles agglomerate rather than remaining well-dispersed. Additionally, problems may occur if the transfer comprises high-temperature treatment of the nanoparticles.
Some methods have been developed for transferring the nanoparticles from organic liquid to water by exchanging hydrophobic ligands of the nanoparticle-containing complexes with hydrophilic ligands. However, such exchange may lead to particle agglomeration and/or may utilize high-temperature processing and multiple solvents. Accordingly, it is desired to develop new methods for transferring nanoparticles from organic solvent to water.